We need to be driving test numbers up until only 3-5% are showing positive in order to be confident about low prevalence in an area. I don't see a problem with false positives encouraging asymptomatic people to get tested - it's as good of a sub-population as any.

The project lead of Singapore's TraceTogether initiative goes into detail about the problems with an automated system, and why a human-in-the-loop is ideally required to evaluate the type of contact and make a determination.

A determination around being a close contact results in 14-day isolation regardless of symptoms, presumably because you may initially test negative before moving into an infectious and asymptomatic or symptomatic phase.

https://blog.gds-gov.tech/automated-contact-tracing-is-not-a...

It's worth re-iterating how unreliable bluetooth signal strength is in estimating proximity.

One recent data point using the CovidSafe app is here: https://twitter.com/jim_mussared/status/1256199078314078210

Exploration around the defects in that app is ongoing here: https://docs.google.com/document/d/1u5a5ersKBH6eG362atALrzuX...

14 day isolation was a policy choice. There is no reason that other municipalities do the same. We can discover a balance that keeps local r < 1.0

I assume that the use model is as a way to help human contact tracing, not to replace. Admittedly, the benefit is less then, but maybe it's still worth it?

The assumptions of benefit appear to rely on a naive theory of instantaneous contact and isolation, when in practice the entire process is unavoidably manual, requiring human intelligence to ascertain environmental factors with which to make a determination about whether someone is a close contact.

When you consider that close contacts include anyone you've spent more than 2 hours with in a room, it becomes clear that most life situations are not handled by estimates of proximity using bluetooth: home, family & friend visits, workplaces.

You can find a deep-dive into these issues here:

https://blog.crushthecurve.today/why-should-you-install-the-...